This invention relates generally to devices for improving the efficiency of internal combustion engines and more particularly concerns an improved device for atomizing and dispersing the fuel in a fuel/air mixture within the intake manifold of an internal combustion engine.
It is known that if the fuel in the fuel/air mixture of an internal combustion engine is highly atomized and dispersed, the efficiency of the engine will be improved and objectionable emissions from the engine reduced. In a conventional internal combustion engine, fresh air is drawn through a carburetor by the vacuum created by the downward stroke of the engine's pistons. The air passes through a venturi and past an orifice through which liquid fuel is supplied. The airstream draws the liquid fuel from the orifice, and the fuel and air mix. The fuel and air mixture then passes the throttle plate of the carburetor, into the intake manifold, and into the open intake valve of each cylinder.
Conventional carburetors are not particularly good mixers of fuel and air. The resulting fuel particles in the fuel and air mixture may be of a relatively large size. During startup and slow idle, the fuel particles may actually coalesce and form puddles within the intake manifold thus further increasing the size of the fuel particles.
Many attempts have been made to reduce the size of the fuel particles and increase dispersion of the fuel in the fuel/air mixture in the intake manifold of internal combustion engines. The prior art discloses numerous devices including atomizers which purportedly decrease the fuel particle size and increase dispersion of the liquid fuel in the fuel/air mixture thereby improving the efficiency of the engine and reducing the emissions of the engine. Some prior art atomizers have consisted simply of screens or nonwettable plates within the fuel/air mixture stream. Other prior art atomizers have utilized a rotor or propeller which spins in response to the moving fuel/air mixture to further mix the fuel and air.
The prior art discloses numerous rotor and propeller-type atomizers including U.S. Pat. No. 4,153,028 issued to Kumm et al.; U.S. Pat. No. 4,014,306 issued to Ingersoll; U.S. Pat. No. 4,011,850 issued to Knox; U.S. Pat. No. 3,945,361 issued to Piotrowicz; U.S. Pat. No. 3,615,296 issued to Guarnaschelli; U.S. Pat. No. 3,544,290 issued to Larson et al.; U.S. Pat. No. 3,490,883 issued to Olivie; U.S. Pat. No. 3,283,482 issued to Trafford et al.; U.S. Pat. No. 1,153,077 issued to Hippel; and U.S. Pat. No. 1,051,369 issued to Heath.
In order, however, for a propeller-type atomizer to be practical, it is necessary for the atomizer to be long-lived, sturdy in construction, and simple to manufacture.
Bearing failure is a common problem for propeller-type atomizers. The propeller in the atomizer may spin at up to 5,700 rpm during operation. The fuel/air environment can cause lubrication failure. And the wide range of temperatures encountered can cause warping and bearing misalignment.
In order to extend bearing life, U.S. Pat. No. 3,615,269 to Guarnaschelli discloses the use of a second set of blades on the propeller that are reverse tilted in order to slow the speed of rotation.
Lubrication of the bearings for the propeller presents a formidable problem. The fuel droplets in the fuel/air mixture can penetrate into the bearing, dissolve most lubricants, and effectively flush the lubricants from the bearings. The result, of course, is premature bearing failure from lack of lubrication. Olivie, U.S. Pat. No. 3,490,883, specifically provides for a channel in one of the ends of the bearing to convey lubrication (such as ricinolic oil) to the bearing from outside of the manifold.
In modern engines, the temperature encountered in the intake manifold can vary from ambient to 700.degree. F. during operation and to as much as 1600.degree. F. shortly after the engine has been turned off. As a result, it is important to provide a housing that can resist the extremes in temperature without warping and thereby subjecting the bearings to excessive stresses during subsequent operation.
The housing and bearing support system of the atomizer must be constructed so that the bearings are properly and consistently aligned during assembly and rigidly supported during operation. Proper bearing alignment helps assure longer bearing life.
Finally, if the atomizer fails during operation, it is important to assure that the failed parts cannot be ingested into the engine causing damage to the engine. As a result, prior art propeller-type atomizers have had a substantial spiderweb-like grill at the downstream end to catch and hold the failed parts so that the pieces cannot be ingested into the automobile engine. Such a grill, however, creates a substantial restriction in the flow of the fuel/air mixture and thereby degrades engine performance.